ChatGPT Plus has a list price of $20 per month, but the actual amount you pay...

https://wiki-planet.win/index.php/Are_Modified_Android_Apps_Real_ChatGPT_Plus_Access%3F

ChatGPT Plus has a list price of $20 per month, but the actual amount you pay can range from about $13 to $27. This difference is due to factors like local taxes such as VAT or GST and extra fees charged by app stores for iOS and Android